The episodic memory system was described by Endel Tulving as the human capacity for mental time travel. By this we mean that if you focus your mind in the present moment you can re-experience events from the past and imagine yourself in the future. Episodic memory is amongst the most sophisticated cognitive functions understood by psychologists and neuroscientists. The ability to use episodic memory reliably does not crystallise until approximately 3 years of age, long after other less demanding cognitive functions are established. At the other end of the human lifespan, a decline in the power of episodic memory is associated with healthy ageing before other aspects of cognitive decline set in. Without episodic memory we would not be able to retain the information about what we have done in the past that supports our sense of what makes us unique human beings. The very sense of self that we carry with us through our lives is thought to emerge from episodic memory.
Psychology and neuroscience research over the past 40 years provides us with a generally clear understanding of the basic mechanisms that contribute to episodic memory but there are still a great number of things we do not yet know.
The applied face recognition problem
While recognition of a familiar face across two different photographs is a trivial problem for humans, our ability to determine whether two photos of the same unfamiliar person depict the same person or not is much more difficult. In fact, research has shown that we are only around 70% accurate in simple face matching tasks designed to mimic the function of Border Control staff when scrutinizing passports, which means that we get it wrong 30% of the time. It has even been demonstrated that we have a bias towards accepting that two different faces match when a live human stands next to a photograph of a different person. The applied face problem is therefore concerned with understanding why we are so poor at recognising unfamiliar faces and developing ways to improve performance. The Bridging the Gap project is designed to address the applied face recognition problem by making use of cognitive neuroscience methods that have been developed in pioneering episodic memory research.
Episodic memory is usually investigated in the laboratory using one of two types of test - recall or recognition memory. In a recall test people are asked to report what they can remember either about their own past experience or about information they were exposed to in the laboratory. In a recognition memory task, on the other hand, people are shown stimuli that they were exposed to previously and asked whether or not they remember it. Recognition memory tasks give experimenters more control over what types of stimuli can be used to cue retrieval and when access to memory occurs. In an applied setting, people who have witnessed a crime perform a kind of recognition memory task when they are asked to pick a perpetrator out from an identity parade. The Bridging the Gap project seeks to discover how recognition memory for unfamiliar faces can be improved by asking research participants to do different things when they are exposed to faces in the laboratory. You can read about our findings as they become available here.